Pretty print binary tree in Racket

#lang racket
(require racket/include)
(require pict)
(require pict/tree-layout)
(require pict/color)
(require racket/format)

(include "set.scm")

(define (liste->baum lst)
  (define (rek-lst-bm lst bm)
    (if (empty? lst)
        bm
        (rek-lst-bm (cdr lst) (adjoin-set (car lst) bm)))
    )
  (rek-lst-bm lst the-empty-tree)
)

(define (print-tree bm)
  (define (print-entry num left right)
    (tree-layout #:pict(cc-superimpose (gray(filled-ellipse 20 20)) (text (~a num))) left right)
  )
  (define (print-empty-entry)
    ; make the lines end at the top of squares
    (tree-layout #:pict(cbl-superimpose (blank 20) (gray (rectangle 10 10))))
  )
  (define (gen-tree bm)
    (if (empty-tree? bm)
    (print-empty-entry)
    (print-entry (entry bm) (gen-tree (left-branch bm)) (gen-tree (right-branch bm))))
  )
  (naive-layered (gen-tree bm))
)

(print-tree (liste->baum '(5 2 6 4 5)))